Preparation of carbon-11 labelled acetate and palmitic acid for the study of myocardial metabolism by emission-computerised axial tomography

Methods have been developed for the labelling of acetate and palmitic acid with the positron-emitting radionuclide,¹¹C (T=20.4 min). Labelling was achieved via carbonation of the appropriate alkyl magnesium bromide (methyl magnesium bromide or n-pentadecyl magnesium bromide) with¹¹C-labelled carbon dioxide produced by the¹⁴N(p, α)¹¹C nuclear reaction. The radiochemical yield and speed of each method of labelling are such that a radiochemically pure product is obtained in injectable form and in activity (>10 mCi) suitable for the study of myocardial metabolism by emission-computerised axial tomography. High pressure liquid chromatography and thin layer chromatography were used to assess the radiochemical purity of each radiopharmaceutical. The specific activity of¹¹C-labelled acetate was estimated by an enzymic procedure to be greater than 0.5 Ci/μmole.